Hi Jim, Thanks for the resistance vs. temp figures.
Sensor positions - now that is interesting! I have two sensors on the stat housing, one underneath with the rectangular socket and one on top with a roundish plug on a "not round" socket. Long ago when I built my H4 I mapped both the Fiesta and Escort harnesses for Old Q for the H4 "Kit-in-a-box" to allow for using the Escort 1800 Zetec engine attached to a modified Fiesta loom. Whether the paperwork for this has survived the fire is unknown at present - I have the folder but it is covered in black soot which permeated everything in its path! Eddy might well have copies as these were supplied to Old Q and I saw these at the Sampson establishment. It is the underside one with rectangular socket that gives this rapid resistance change at ~ 40°C with the hysteresis whilst the top one gives a steady change (even if logarithmic) with temperature. My understanding was that the ECU sensor effectively acts like a flip-flop going from high to low at the changeover point at ~40°C - depends upon how it is connected as to which state is a 1 or 0 - which then flips between maps on the ECU. That is how we set up the diesel ECU systems at work. With any luck I might have some small time tomorrow to try shorting the pins on the rectangular socket. I recollect that it was when I removed the top plug that the gauge went to zero - but then I am getting old..........! -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jim Hearne Sent: 14 March 2012 15:01 To: [email protected] Subject: Re: [Quantum Owners] Re: Low Reading Temperature Gauge What happens if you link together the 2 pins of the temp gauge sensors ?, it should go up to max. This is the one with the smaller rectangular plug on the front of the stat housing, not the larger one with the round connector on the side. Jim -------------------------------------------------- From: "Hamish Freeman" <[email protected]> Sent: Wednesday, March 14, 2012 2:46 PM To: <[email protected]> Subject: RE: [Quantum Owners] Re: Low Reading Temperature Gauge > Yes that is what I thought so I tested each of the sensors to see what > happened with temperature. The gauge sensor is, as stated, a > "straight forward" thermistor but the ECU sensor is designed to switch > from high resistance to low resistance at ~ 40°C to ensure that the > ECU switches from the "Cold Map" to the "Hot Map" at the earliest > opportunity to save both on economy and the generation of HC. This > device also has a high level of hysteresis built in to ensure that the > system does not accidentally switch back to the "Cold Map" should the > engine undergo some freak overcooling - I had to immerse the switch in > cold water to get it to switch back after heating whilst the > transition from high to low resistance takes place over about 5°C > around 40°C. I was surprised at this response so I checked this three > times and the above characteristics were repeated each time. > > Whilst the car is not suffering from poor performance, I will check > the inlet manifold temperature sensor as I had forgotten that! Thanks > for the tip! > > This really is a matter of having everything working properly and > giving readings that are believable. A low reading temperature gauge > is more of a distraction than anything else as it is not calibrated in > any scale but if it is not indication in the right region I start to > wonder if anything is wrong. > > The worst thing in that respect is the speedo on Trish's Micra, which > reads ~9.8% high. We complained to Nissan shortly after we bought it > to receive the reply "If it is within 10% then it is legal and we are > not going to change it!". Since the speedo is driven by the ECU and > recalibration is simply a number change in the ECU via the device they > use to reset the service interval, I was not impressed. After last > year when they charged us 50% more for the last service done under the > guarantee and only completed half of it as well as cross threading the > sump plug (for which they tried to put the blame on me whilst they are > the only people to have touched it) and not finding the air-con pipe > that had worked its way loose, we will not be returning to that > garage, even to keep the computer record up to date. > > Hamish -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s).
